Fix false negative in -Wthread-safety-attributes

[aaronpuchert]

Summary

The original implementation didn't fire on non-template classes when a
base class was an instantiation of a template with a dependent base.
In that case the base of the base is dependent as seen from the base,
but not from the class we're interested in, which isn't a template.

Also it simplifies the code a lot.

[aaronpuchert]

Ping @aaron.ballman.

[aaron.ballman]

LGTM, thanks!

clang/lib/Sema/SemaDeclAttr.cpp

 template <typename AttrType>
 static bool checkRecordDeclForAttr(const RecordDecl *RD) {
   // Check if the record itself has the attribute.
   if (RD->hasAttr<AttrType>())
     return true;
 
   // Else check if any base classes have the attribute.
   if (const auto *CRD = dyn_cast<CXXRecordDecl>(RD)) {
-    CXXBasePaths BPaths(false, false);
-    if (CRD->lookupInBases(
-            [](const CXXBaseSpecifier *BS, CXXBasePath &) {
-              const auto &Ty = *BS->getType();
-              // If it's type-dependent, we assume it could have the attribute.
-              if (Ty.isDependentType())
-                return true;
-              return Ty.castAs<RecordType>()->getDecl()->hasAttr<AttrType>();
-            },
-            BPaths, true))
+    if (!CRD->forallBases([](const CXXRecordDecl *Base) {
+          return !Base->hasAttr<AttrType>();
+        }))
       return true;
   }
   return false;
 }
 
 static bool checkRecordTypeForCapability(Sema &S, QualType Ty) {
   const RecordType *RT = getRecordType(Ty);
 

clang/test/SemaCXX/warn-thread-safety-parsing.cpp

struct SLDerived1 : public SLTemplateClass<double> {
   ~SLDerived1() UNLOCK_FUNCTION();
 };
 
 struct SLDerived2 : public SLTemplateClass<int> {
   ~SLDerived2() UNLOCK_FUNCTION(); // \
     // expected-warning{{'unlock_function' attribute without capability arguments refers to 'this', but 'SLDerived2' isn't annotated with 'capability' or 'scoped_lockable' attribute}}
 };
 
+struct SLDerived3 : public SLTemplateDerived<int> {
+  ~SLDerived3() UNLOCK_FUNCTION(); // \
+    // expected-warning{{'unlock_function' attribute without capability arguments refers to 'this', but 'SLDerived3' isn't annotated with 'capability' or 'scoped_lockable' attribute}}
+};
+
 //-----------------------------------------------------
 // Parsing of member variables and function parameters
 //------------------------------------------------------
 
 Mutex gmu;
 
 class StaticMu {
   static Mutex statmu;